Li2MnO3 Cathode Doping and Pre-Charge for Capacity
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Solution Overview
Problem
Lithium secondary batteries face limitations in capacity and service life due to issues with Li2MnO3 cathode active materials, including irreversible reactions, oxygen generation, and nonconductive coating formation, which reduce charge and discharge capacity and increase pressure.
Innovation Solution
A cathode active material is developed by doping Li2MnO3 with fluoro compounds and elements like W, Mo, and Cr, which reduces oxygen production, stabilizes the manganese oxidation state, and enhances particle compactness through controlled heat treatment, thereby improving specific capacity and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li2MnO3 is used as cathode active material to increase lithium content, then battery capacity is improved, but irreversible reaction occurs during initial charge and capacity is lowered during actual charge and discharge
Solution Approach 1:
The patent applies preliminary action by conducting a pre-treatment charge at a low voltage cutoff of 3.0V before the battery enters normal operation. This preliminary charge removes excess lithium from the cathode material, preventing irreversible reactions during subsequent initial charging cycles. The pre-treatment step stabilizes the cathode material structure, enabling the high lithium content material to function reliably during normal charge and discharge operations while maintaining high capacity.
2Quantity of substance
If Li2MnO3 is used as cathode active material, then lithium content is increased, but oxygen is generated and pressure in battery is increased
Solution Approach 1:
The patent applies preliminary action by conducting a pre-treatment charge at a low voltage cutoff of 3.0V before normal battery operation. This preliminary step prevents oxygen generation by avoiding the high-voltage conditions that cause oxygen release from the cathode material. By stabilizing the structure in advance, the patent eliminates the harmful oxygen generation effect during normal operation while maintaining high lithium content.
3Quantity of substance
If Li is deintercalated at high voltage of 4.4V or more, then charge and discharge capacity is improved, but phase change occurs and oxygen is produced
Solution Approach 1:
The patent applies preliminary action by conducting a pre-treatment charge at a low voltage cutoff of 3.0V to stabilize the cathode material structure before normal operation. This preliminary stabilization prevents phase changes and oxygen production that would occur if the material were directly subjected to high-voltage deintercalation (4.4V or more). The pre-treatment step creates a stable structure that can subsequently handle high-voltage operation without decomposing.
4Quantity of substance
If Li2MnO3 is used as cathode active material, then specific capacity is improved, but service life is reduced due to side reactions with electrolyte
Solution Approach 1:
The patent applies preliminary action by conducting a pre-treatment charge at a low voltage cutoff of 3.0V to stabilize the cathode material surface before normal battery operation. This preliminary step forms a stable surface structure that prevents side reactions with the electrolyte during subsequent cycling. By stabilizing the surface in advance, the patent extends service life while maintaining the high specific capacity of the Li2MnO3 material.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the service life and rate capability of lithium secondary batteries by suppressing side reactions, reducing irreversible capacity, and increasing energy density, while maintaining high press density and specific capacity.
Implementation Method 1
a lithium metal composite compound in which Li 2 MnO 3 having a layered structure containing lithium in excess is doped with a fluoro compound and one or more of W, Mo, V and Cr ion having +1 to +6 of multiple oxidation states
Implementation Method 2
mixing one or more elements with a multiple oxidation state selected from the group consisting of W, Mo, V, and Cr, a fluoro compound, a lithium supply source, and a transition metal compound precursor, and then heat-treating the mixture at 600°C to 800°C
Data Source
AI summary
The present invention relates to a cathode active material for a lithium secondary battery, a method for preparing the same, and a lithium secondary battery including the same, and provides a cathode active material including Li2MnO3 having a layered structure, and doped with one or more elements with a multiple oxidation state selected from the group consisting of W, Mo, V, and Cr, and a fluoro compound.